Exploring the relationships between shear zones and granites: field and microstructural data for contrasting case studies of the Borborema Province (NE Brazil)

We discuss meso- and microstructural features of granites closely related to strike-slip shear zones in the Borborema Province, NE Brazil. The Riacho do Icó stock is an en-cornue intrusion aged at ca. 607 Ma. Magmatic fabric is recorded in the core of the granite, whilst increasing deformation is marked by the development of mylonitic fabrics towards the Afogados da Ingazeira shear zone, including magmatic foliation and lineation rotation. Early recrystallization of quartz and K-feldspar crystals is widespread as a fabric with well-developed granoblastic polygonal textures and lobate subgrain boundaries, heterogeneously deformed lenses and ameboid quartz ribbons, typical of igneous rocks submitted to deformation in deep crustal levels. On the other hand, the Espinho Branco-Santa Luzia leucogranitic belt is hosted along the Patos Lineament, aged between the ca. 575 – 565 Ma interval. These rocks show discordant relationships with the host migmatites and the main deformational fabric is characterized by a dominant magmatic foliation that is locally overprinted by structures that are typical of solid-state flow. Quartz melt pockets and interstitial quartz grains filling fractures in feldspar clasts are common. Such characteristics are compatible with granites that were injected in the continental crust along planar anisotropies (i.e., shear zones) formed during the late-stage partial melting events that originated the migmatites of the area. The case studies are proxies in the understanding of different episodes of magma emplacement along shear zones in this part of West Gondwana.

Geospatial Management and Analysis of Microstructural Data from San Andreas Fault Observatory at Depth (SAFOD) Core Samples

Core samples obtained from scientific drilling could provide large volumes of direct microstructural and compositional data, but generating results via the traditional treatment of such data is often time-consuming and inefficient. Unifying microstructural data within a spatially referenced Geographic Information System (GIS) environment provides an opportunity to readily locate, visualize, correlate, and apply remote sensing techniques to the data. Using 26 core billet samples from the San Andreas Fault Observatory at Depth (SAFOD), this study developed GIS-based procedures for: 1. Spatially referenced visualization and storage of various microstructural data from core billets; 2. 3D modeling of billets and thin section positions within each billet, which serve as a digital record after irreversible fragmentation of the physical billets; and 3. Vector feature creation and unsupervised classification of a multi-generation calcite vein network from cathodluminescence (CL) imagery. Building on existing work which is predominantly limited to the 2D space of single thin sections, our results indicate that a GIS can facilitate spatial treatment of data even at centimeter to nanometer scales, but also revealed challenges involving intensive 3D representations and complex matrix transformations required to create geographically translated forms of the within-billet coordinate systems, which are suggested for consideration in future studies.

Silver Nanoparticles Impregnated Zeolites Derived from Coal Fly Ash: Effect of the Silver Loading on Adsorption of Mercury (II)

Removal of mercury (II) from aqueous phase is of utmost importance, as it is highly toxic and hazardous to the environment and human health. A promising method for the removal of mercury (II) ions from aqueous solutions is by using adsorbents derived from coal fly ash (CFA), such as synthetic zeolites. In this work we present the hydrothermal production of synthetic zeolites from CFA followed by a modification for impregnation of silver nanoparticles, in solid concentrations from 0.15 to 4.71 wt.%. All produced zeolites and parent materials are characterized by XRD, XRF, BET and PSA to obtain morphological and microstructural data. Moreover, mercury (II) ions removal from aqueous solutions with initial concentration of 10 ppm is studied. According to results, zeolites and Ag-nanocomposites demonstrate much higher removal than parent CFA (up to 98%). In addition to this, we could observe a distinct adsorption behavior depending on the loading of Ag NPs in nanocomposites. A possible removal mechanism for both zeolites and Ag-nanocomposites is discussed.

Composition and texture of a set of marvered glass vessels from 12th century ad Branicevo, Serbia

Strongly coloured glass vessels decorated with marvered threads of white glass are a wide-spread and popular, but rarely studied group of high-quality glassware of medieval Islamic origin. Relatively little is known about the composition and production places of these vessels, and their chronological range is not very well defined, as many of the published finds lack contextual evidence. Here, we present detailed chemical and microstructural data on a set of well-dated purple glass vessels decorated with white threads, excavated at the Mali Grad site in Branicevo, Serbia, in an archaeological context dated to the middle/second half of the 12th century AD. The set comprises at least sixteen different vessels, manufactured from two different batches of probably Levantine plant-ash glass coloured by manganese oxide. Significantly, the results demonstrate that these batches are correlated to particular vessel shapes. The base glass of the white threads is comparable to that of the purple vessel glass, but instead of being coloured by added manganese oxide, it contains considerable amounts of tin and lead oxides which provide the effect of opacity and white colour. No difference in composition can be seen between the white glass threads used to decorate the vessels from the two different manganese-coloured batches, thus indicating a likely common production origin of the whole set.